When you have a ultrabook or a laptop with a HDD Caddy, you do not have an optical drive anymore in your laptop. However you can still perform a new clean Windows 7 installation by using a USB-stick (of course an external DVD-drive also works). This often goes much faster than the installation from an optical medium (like a DVD). Microsoft released a very easy-to-use and simple software tool to burn a .ISO file from a Windows 7 installation disc to a bootable USB stick which you can immediately use to install Windows 7 on a laptop or PC. Of course you can also use this USB stick on a PC with an optical drive that doesn’t work anymore or doesn’t read DVD’s. When your bootable Windows Installation USB stick is ready to go, make sure that your laptop or PC select the USB stick as the first boot device in order to start the Windows installation. You can change this boot order in the BIOS settings. Some laptops do have a boot selection function during the boot. For instance if you have a Dell laptop you can hit F12 when you turn on your laptop and it will show a menu where you select from which device you want to boot (USB stick in this case). When you are done with the installation you can put the BIOS settings back so that the first boot device is your new installed Windows hard drive or SSD.
You can download the program here from Microsoft website: https://www.microsoftstore.com/store/msusa/html/pbPage.Help_Win7_usbdvd_dwnTool
The Setup is very easy most steps speak for itself.
1. Install the program
2. Start the program when done
3. Choose the .ISO file of your Windows installation disc
4. Choose the USB stick where you want to install the Windows 7 setup, it must be higher than 4GB
5. Start installation proces
6. When the installation process has completed your USB-stick is then a bootable USB stick that contains the Windows 7 setup!